"500,000 malnourished children in the developing world go blind each year from a deficiency of vitamin A, around half of whom die within a year of becoming blind. The United Nations Special Session on Children in 2002 set a goal of the elimination of VAD by 2010. The prevalence of night blindness due to VAD is also high among pregnant women in many developing countries. VAD also contributes to maternal mortality and other poor outcomes in pregnancy and lactation. VAD also diminishes the ability to fight infections. In countries where children are not immunized, infectious diseases such as measles have"
"bombers, the British Royal Ministry told newspapers that the nighttime defensive success of Royal Air Force pilots was due to a high dietary intake of carrots rich in vitamin A, propagating the myth that carrots enable people to see better in the dark. Vitamin A Vitamin A is a group of unsaturated nutritional organic compounds that includes retinol, retinal, retinoic acid, and several provitamin A carotenoids (most notably beta-carotene). Vitamin A has multiple functions: it is important for growth and development, for the maintenance of the immune system and good vision. Vitamin A is needed by the retina of the"
"is composed of the 11-cis-retinal covalently linked via a Schiff base to the opsin protein (either rod opsin or blue, red or green cone opsins). The process of vision relies on the light-induced isomerisation of the chromophore from 11-""cis"" to all-""trans"" resulting in a change of the conformation and activation of the photoreceptor molecule. One of the earliest signs of vitamin A deficiency is night-blindness followed by decreased visual acuity. George Wald won the 1967 Nobel Prize in Physiology or Medicine for his work with retina pigments (also called visual pigments), which led to the understanding of the role of"
"protein rhodopsin, the visual pigment used in low light levels. This represents the first step of the visual cycle. This is why eating foods rich in vitamin A is often said to allow an individual to see in the dark, although the effect they have on one's vision is negligible. In fact, excess vitamin A intake can cause toxicity to the optic nerve and permanent vision loss. Vitamin A is essential for the correct functioning of epithelial cells. In vitamin A deficiency, mucus-secreting cells are replaced by keratin producing cells, leading to xerosis. Glycoprotein synthesis requires adequate vitamin A status."
"supplied by vitamin A in the diet. Deficiency of all-""trans"" retinal can lead to night blindness. This is part of the bleach and recycle process of retinoids in the photoreceptors and retinal pigment epithelium. Phototransduction process in invertebrates like the fruit fly is different from the vertebrates. PI(4,5)P cycle underlies the phototransduction process. Here, light induces the conformational change into Rhodopsin and converts it into meta-rhodopsin. This helps in dissociation of G -protein complex. Alpha sub-unit of this complex activates the PLC enzyme (PLC-beta) which hydrolyze the PIP2 into DAG. This hydrolysis leads to opening of TRP channels and influx"
"that was heated and aerated so its vitamin A was destroyed. The oil could no longer cure night blindness but did cure rickets. After his rats recovered, he named the substance for the next free letter of the alphabet, vitamin D. Then they became convinced that sunshine and cod-liver oil both protected against rickets, and tested this by carrying rats outside to the sunshine. Soon after, a generation of children grew up on cod-liver oil, and rickets was virtually wiped out. Harry Day, a colleague and McCollum biographer, writes that finding vitaminD was the work of ""a host of investigators"""
"under 5 each year. Vitamin A supplementation costs only $0.02 for each capsule and given 2–3 times a year will prevent blindness and death. Although vitamin A supplementation has been shown to reduce all-cause mortality by 12 to 24 per cent, only 70 per cent of targeted children were reached in 2015. Between 250,000 and 500,000 children become blind every year, with 70 percent of them dying within 12 months. Oral rehydration therapy (ORT) is an effective treatment for lost liquids through diarrhea; yet only 4 in 10 (44 per cent) of children ill with diarrhea are treated with ORT."
"it could be converted into free retinol. The American scientist George Wald was the first to recognize that the visual system expends vitamin A and is dependent upon diet for its replacement. Vitamin A serves many functions in the human body outside of healthy vision. It is vital in maintaining a healthy immune system as well as promoting normal growth and development. The average adult male and female should consume 900 and 700 micrograms of vitamin A per day, respectively. Consumption above 3000 micrograms per day is referred to as vitamin A toxicity and is usually caused by accidental ingestion"
"of ultraviolet light therapy and medicine. Recommendations are for 400 international units (IU) of vitamin D a day for infants and children. Children who do not get adequate amounts of vitamin D are at increased risk of rickets. Vitamin D is essential for allowing the body to uptake calcium for use in proper bone calcification and maintenance. Sufficient vitamin D levels can also be achieved through dietary supplementation and/or exposure to sunlight. Vitamin D (cholecalciferol) is the preferred form since it is more readily absorbed than vitamin D. Most dermatologists recommend vitamin D supplementation as an alternative to unprotected ultraviolet"
"children who suffer from vitamin A deficiency (VAD). In 2005, 190 million children and 19 million pregnant women, in 122 countries, were estimated to be affected by VAD. VAD is responsible for 1–2 million deaths, 500,000 cases of irreversible blindness and millions of cases of xerophthalmia annually. Children and pregnant women are at highest risk. Vitamin A is supplemented orally and by injection in areas where the diet is deficient in vitamin A. , 43 countries had vitamin A supplementation programs for children under 5; in 10 of these countries, two high dose supplements are available per year, which, according"
"of animal origin. Each of the following contains at least 0.15 mg of retinoids per : Synthetic retinol is marketed under the following trade names: Acon, Afaxin, Agiolan, Alphalin, Anatola, Aoral, Apexol, Apostavit, Atav, Avibon, Avita, Avitol, Axerol, Dohyfral A, Epiteliol, Nio-A-Let, Prepalin, Testavol, Vaflol, Vi-Alpha, Vitpex, Vogan, and Vogan-Neu. There are three known routes to retinol that are used industrially, all of which start with β-ionone. Night blindness—the inability to see well in dim light—is associated with a deficiency of vitamin A. At first, the most light sensitive (containing more retinal) protein rhodopsin is influenced. Less pigmented retinal iodopsins"
"is colorless. Riboflavin Riboflavin, also known as vitamin B, is a vitamin found in food and used as a dietary supplement. Food sources include eggs, green vegetables, milk and other dairy product, meat, mushrooms, and almonds. Some countries require its addition to grains. As a supplement it is used to prevent and treat riboflavin deficiency and prevent migraines. It may be given by mouth or injection. It is nearly always well tolerated. Normal doses are safe during pregnancy. Riboflavin is in the vitamin B group. It is required by the body for cellular respiration. Riboflavin was discovered in 1920, isolated"
"needs. The golden rice project is one such effort, and is already undergoing trials. Retinol Retinol, also known as Vitamin A, is a vitamin found in food and used as a dietary supplement. As a supplement it is used to treat and prevent vitamin A deficiency, especially that which results in xerophthalmia. In areas where deficiency is common, a single large dose is recommended to those at high risk a couple of times a year. It is also used to prevent further issues in those who have measles. It is used by mouth or injection into a muscle. Retinol at"
"formulations for these reasons. A more recent study investigated the effects of lutein and zeaxanthin on macular pigment and visual function in patients with early AMD. Daily intake of either 20 mg lutein alone or 10 mg lutein and 10 mg zeaxanthin was found to significantly increase the macular pigment content in comparison with the placebo group; the authors also reported a significant improvement in contrast sensitivity and a trend toward improvement in best-corrected visual acuity after 48 weeks of carotenoid supplementation. Furthermore, they found a significant correlation between these two parameters of visual function and the macular pigment content,"
"at night, but also require extra time for their eyes to adjust from brightly lit areas to dim ones. Contrast vision may also be greatly reduced. Rods contain a receptor-protein called rhodopsin. When light falls on rhodopsin, it undergoes a series of conformational changes ultimately generating electrical signals which are carried to the brain via the optic nerve. In the absence of light, rhodopsin is regenerated. The body synthesizes rhodopsin from vitamin A, which is why a deficiency in vitamin A causes poor night vision. Refractive ""vision correction"" surgery (especially PRK with the complication of ""haze"") may rarely cause a"
"dies before age 5; and 1 in 16 children in Southern Asia. Given that vitamin A is critical for proper functioning of the visual system and for maintaining immune defences, its deficiency remains a public health issue. An estimated 250,000 to 500,000 children deficient in vitamin A become blind every year, half of them dying within 12 months of losing their sight. This deficiency accounts for 350 million cases of blindness and 670,000 deaths globally (WHO, 2001). In Africa alone, it contributes to 23 per cent of child deaths. In 2009, the prevalence of low serum retinol, associated with vitamin"
"reduction in best night-time acuity due to the impairment of contrast sensitivity function (CSF) which is induced by intraocular light-scatter resulting from surgical intervention in the natural structural integrity of the cornea. Aulus Cornelius Celsus, writing ca. 30 AD, described night blindness and recommended an effective dietary supplement: ""There is besides a weakness of the eyes, owing to which people see well enough indeed in the daytime but not at all at night; in women whose menstruation is regular this does not happen. But success sufferers should anoint their eyeballs with the stuff dripping from a liver whilst roasting, preferably"
"light emitted by the moon during the night. It can be extrapolated that the high ratio of rods to cones present in modern human eyes was retained even after the shift from nocturnal back to diurnal. Vitamin A is necessary for proper functioning of the human eye. The photopigment rhodopsin found in human rod cells is composed of retinal, a form of vitamin A, bound to an opsin protein. Upon the absorption of light rhodopsin was decomposed into retinal and opsin through bleaching. Retinal could then have one of two fates: it could recombine with opsin to reform rhodopsin or"
"progression remains an unresolved, yet prospective treatment option. Clinical trials investigating optic prosthetic devices, gene therapy mechanisms, and retinal sheet transplantations are active areas of study in the partial restoration of vision in retinitis pigmentosa patients. Studies have demonstrated the delay of rod photoreceptor degeneration by the daily intake of 15000 IU (equivalent to 4.5 mg) of vitamin A palmitate; thus, stalling disease progression in some patients. Recent investigations have shown that proper vitamin A supplementation can postpone blindness by up to 10 years (by reducing the 10% loss pa to 8.3% pa) in some patients in certain stages of"
"skin, or hypervitaminosis A. High doses during pregnancy may result in harm to the baby. Retinol is in the vitamin A family. It or other forms of vitamin A are needed for eyesight, maintenance of the skin, and human development. It is converted in the body to retinal and retinoic acid through which it acts. Dietary sources include fish, dairy products, and meat. Retinol was discovered in 1909, isolated in 1931, and first made in 1947. It is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system. Retinol is"
"quickly. Folate also plays an important role in the development of many neurotransmitters, e.g. serotonin which regulates appetite, sleep, and mood. Serum folate is broken down by UV radiation or alcohol consumption. Because the skin is protected by the melanin, dark pigmented people have a lower chance of developing skin cancer and conditions related to folate deficiency, such as neural tube defects. Dark-skinned people living in low sunlight environments have been recorded to be very susceptible to vitamin D deficiency due to reduced vitamin D synthesis. A dark-skinned person requires about six times as much UVB than lightly pigmented persons."
"hydroquinolones (amebicidal medications), ethambutol and isoniazid (tuberculosis treatment), and antibiotics such as linezolid and chloramphenicol. Tobacco is also a major cause of toxic optic neuropathy. The predominant cause of nutritional optic neuropathy is thought to be deficiency of B-complex vitamins, particularly thiamine (vitamin B), cyanocobalamin (vitamin B) and recently copper. Deficiency of pyridoxine (vitamin B), niacin (vitamin B), riboflavin (vitamin B), and/or folic acid also seems to play a role. Those individuals who abuse alcohol and tobacco are at greater risk because they tend to be malnourished. Those with pernicious anemia are also at risk due to an impaired ability"
"This protein, found in the retina and the skin, exists in fractional percentages of the normal levels found in homozygous ""Lp/Lp"" horses and so compromises the basic chemical reaction for nerve impulse transmission. Nyctalopia Nyctalopia ( ), also called night-blindness, is a condition making it difficult or impossible to see in relatively low light. It is a symptom of several eye diseases. Night blindness may exist from birth, or be caused by injury or malnutrition (for example, vitamin A deficiency). It can be described as insufficient adaptation to darkness. The most common cause of nyctalopia is retinitis pigmentosa, a disorder"
"from β-carotene, and lesser amounts of α-carotene, γ-carotene, lutein, and zeaxanthin. α- and β-carotenes are partly metabolized into vitamin A, providing more than 100% of the Daily Value (DV) per 100 g serving of carrots (right table). Carrots are also a good source of vitamin K (13% DV) and vitamin B6 (11% DV), but otherwise have modest content of other essential nutrients (table). The provitamin A beta-carotene from carrots does not actually help people to see in the dark unless they suffer from a deficiency of vitamin A. This myth was propaganda used by the Royal Air Force during the"
"been linked to impaired immune system and brain functions. In addition, recent studies have linked vitamin D deficiency to autoimmune diseases, hypertension, multiple sclerosis, diabetes, and incidence of memory loss. Outside the tropics UVR has to penetrate through a thicker layer of atmosphere, which results in most of the UVB reflected or destroyed en route; because of this there is less potential for vitamin D biosynthesis in regions far from the equator. Higher amount of vitamin D intake for dark-skinned people living in regions with low levels of sunlight are advised by doctors to follow vitamin D rich diet or"
"isomerase activity. All-""trans""-retinal is also an essential component of type I, or microbial, opsins such as bacteriorhodopsin, channelrhodopsin, and halorhodopsin. In these molecules, light causes the all-""trans""-retinal to become 13-""cis"" retinal, which then cycles back to all-""trans""-retinal in the dark state. The American biochemist George Wald and others had outlined the visual cycle by 1958. For his work, Wald won a share of the 1967 Nobel Prize in Physiology or Medicine with Haldan Keffer Hartline and Ragnar Granit. Retinal Retinal is also known as retinaldehyde. It was originally called retinene, and renamed after it was discovered to be vitamin A"
"Vitamin A Vitamin A is a group of unsaturated nutritional organic compounds that includes retinol, retinal, retinoic acid, and several provitamin A carotenoids (most notably beta-carotene). Vitamin A has multiple functions: it is important for growth and development, for the maintenance of the immune system and good vision. Vitamin A is needed by the retina of the eye in the form of retinal, which combines with protein opsin to form rhodopsin, the light-absorbing molecule necessary for both low-light (scotopic vision) and color vision. Vitamin A also functions in a very different role as retinoic acid (an irreversibly oxidized form of"
"1998, Shiva’s organisation Navdanya began a campaign against the biopiracy of basmati rice by US corporation RiceTec Inc. In 2001, following intensive campaigning, RiceTec lost most of its claims to the patent. Shiva strongly opposes golden rice, a breed of rice that has been genetically engineered to biosynthesize beta-carotene, a precursor of Vitamin A. It has the potential to assist in alleviating the vitamin A deficiency suffered by a third of preschool-aged children worldwide. Doctor Adrian Dubock says that golden rice is as cheap as other rice and vitamin A deficiency is the greatest reason for blindness and causes 28%"
"problem, known as hemeralopia, that is, inability to see clearly in bright light, is much rarer. The fovea is blind to dim light (due to its cone-only array) and the rods are more sensitive, so a dim star on a moonless night must be viewed from the side, so it stimulates the rods. This is not due to pupil width since an artificial fixed-width pupil gives the same results. Night blindness can be caused by a number of factors the most common of which being vitamin A deficiency. If detected early enough nyctalopia can be reversed and visual function can"
"isn’t a cure or treatment for AMD. The specific daily amounts of antioxidants and zinc used in the study were – 500 milligrams of vitamin C, 400 International Units of vitamin E, 15 milligrams of beta-carotene (equivalent to 25,000 International Units of vitamin A), 80 milligrams of zinc as zinc oxide, and 2 milligrams of copper as cupric oxide. The Age-Related Eye Disease Study 2 (AREDS2) started in 2006 and was completed in 2012. AREDS2 is a second separate study from the original AREDS study. The purpose of this study was to improve and test different combinations of the original"
"deoxyadenosylcobalamin. Hydroxocobalamin Hydroxocobalamin, also known as vitamin B and hydroxycobalamin, is a vitamin found in food and used as a dietary supplement. As a supplement it is used to treat vitamin B12 deficiency including pernicious anemia. Other uses include treatment for cyanide poisoning, Leber's optic atrophy, and toxic amblyopia. It is given by injection into a muscle or vein. Side effects are generally few. They may include diarrhea, low blood potassium, allergic reactions, and high blood pressure. Normal doses are considered safe in pregnancy. Hydroxocobalamin is the natural form of vitamin B and a member of the cobalamin family of"
"high prevalence of vitamin A deficiency. By 2005, Vitamin A deficiency among children 12 to 59 months, as measured by prevalence of night blindness, has decreased to 0.04% from 3.76% in 1982. Kathy Spahn is President and Chief Executive Officer, joining in March 2005. Prior to HKI, Ms. Spahn was President and Executive Director of Orbis, a global non-profit organization dedicated to the prevention and treatment of blindness in the developing world. Helen Keller International is a partner in Compact2025, a partnership that develops and disseminates evidence-based advice to politicians and other decision-makers aimed at ending hunger and undernutrition in"
"evening grosbeak, yellow warbler, common yellowthroat and Javan green magpie) deposit lutein obtained from the diet into growing tissues to color their feathers. Although lutein is concentrated in the macula – a small area of the retina responsible for three-color vision – the precise functional role of retinal lutein has not been determined. In 2013, findings of the Age-Related Eye Disease Study showed that a dietary supplement formulation containing lutein reduced progression of age-related macular degeneration (AMD) by 25 percent. However, lutein and zeaxanthin had no overall effect on preventing AMD, but rather ""the participants with low dietary intake of"